Which protein in the blood is known to bind to drugs, affecting their levels and effects?

Serum albumin is a key protein in the blood that is known for its ability to bind various drugs, impacting their distribution, levels, and therapeutic effects in the body. This protein serves as a carrier for many drugs, as well as for hormones and other substances, allowing for a regulated release into tissues and contributing to the maintenance of proper osmotic pressure in the blood.

When drugs bind to serum albumin, they are often in a non-active or inactive form, which affects the free concentration of the drug that is available to exert its pharmacological effects. The level of serum albumin can therefore significantly alter the efficacy and toxicity of drugs. For example, in conditions where serum albumin levels are low, such as in liver disease or malnutrition, there may be an increased level of free drug in circulation, which can enhance drug effects and lead to potential toxicity.

In contrast, hemoglobin primarily functions in oxygen transport, fibrinogen plays a critical role in blood clotting, and globulins are a group of proteins involved in immune functions and transport. While these proteins have important physiological roles, they do not have the same direct involvement in drug binding and pharmacokinetics as serum albumin does.